A surge most likely, the drivers just suddenly cracked. The speaker amp I use as well as it's headphone socket are fine, but have since bought a headphone amp and connected it to the line/recording out of the stereo amp. I bought a UPS with AVR and surge protection, a cheap one but it does the job and makes no noise.
Currently enjoying two headphones at home, the Koss Porta Pros and Sennheiser PX-100 II. Very happy with those and I'm loving the sound, but I'm planning to purchase something serious within a month or two, especially since I'm going back to making a bit of music of my own. My top candidates right now are the HD 600 and R70X, with the K712 Pro and SRH 1440 also in contention.
Thanks for the curiosity. :)
Edited by LayLay - 2/14/17 at 3:25pm